full contents of that file:

{% for name, user in pillar.get('users', {}).items() if user.vsftpd_user_config is defined %}

{{ name }}_vsftpd_user_conf:
  file.managed:
    - name: /etc/vsftpd/vsftpd_user_conf/{{ name }}
    - source: salt://vsftpd/files/vsftpd_user_conf-TMPL
    - template: jinja
    - watch_in:
      - service: {{ vsftpd.service }}

{% endfor %}

gistfile1.txt

$ sudo salt 'ftp*' state.sls vsftpd 
ftp01.chi5.prlss.int:
    Data failed to compile:
----------
    Rendering SLS 'base:vsftpd.vsftpd_user_config' failed: Jinja variable 'vsftpd' is undefined

init.sls

# vim: sts=2 ts=2 sw=2

{% from "vsftpd/map.jinja" import vsftpd with context %}

vsftpd:
  {% if vsftpd.server is defined %}
  pkg.installed:
    - name: {{ vsftpd.server }}
  {% endif %}
  service.running:
    - enable: True
    - name: {{ vsftpd.service }}
  {% if vsftpd.server is defined %}
    - require:
      - pkg: {{ vsftpd.server }}
  {% endif %}

include:
  - vsftpd.config
  - vsftpd.vsftpd_user_config

vsftpd_user_conf-TMPL

# vim:ft=yaml:
{%- set vsftpd_config = pillar.get('vsftpd_config', {}) -%}
{%- set user = pillar.get('user', {}) -%}
{#- present in vsftpd_config and known in actual file options -#}
{%- set processed_options = [] -%}

{#- generic renderer used for vsftpd known options, -#}
{#- and unknown options -#}
{%- macro render_option(keyword, default, config_dict=vsftpd_config) -%}
  {%- set value = config_dict.get(keyword, default) -%}
  {%- if value is string or value is number -%}
{{ keyword }}={{ value }}
  {%- else -%}
{%- for single_value in value -%}
{{ keyword }}={{ single_value }}
{% endfor -%}
  {%- endif -%}
{%- endmacro -%}

{#- macros for render option according to present -#}
{%- macro option_impl(keyword, default, present) -%}
  {%- if present -%}
    {%- do processed_options.append(keyword) -%}
    {%- set prefix='' -%}
  {%- else -%}
  {#- add prefix to keyword -#}
  {%- set keyword = prefix ~ keyword -%}
{{ render_option(keyword, default) }}
{%- endmacro -%}

{#- macros for render option commented by default -#}
{%- macro option(keyword, default, present) -%}
{{ option_impl(keyword, default, keyword in vsftpd_config) }}
{%- endmacro -%}

{#- macros for render option uncommented by default -#}
{%- macro option_default_uncommented(keyword, default, present) -%}
{{ option_impl(keyword, default, True) }}
{%- endmacro -%}
{{ option('anonymous_enable', 'NO') }}
{{ option('local_enable', 'YES') }}
{{ option('write_enable', 'YES') }}
{{ option('local_umask', '002') }}
{{ option('dirmessage_enable', 'YES') }}
{{ option('xferlog_enable', 'YES') }}
{{ option('dual_log_enable', 'YES') }}
{{ option('pasv_enable', 'YES') }}
{{ option('pasv_promiscuous', 'YES') }}
{{ option('pasv_min_port', '50000') }}
{{ option('pasv_max_port', '55000') }}
{{ option('connect_from_port_20', 'YES') }}
{{ option('vsftpd_log_file', '/var/log/vsftpd.log') }}
{{ option('xferlog_file', '/var/log/xferlog.log') }}
{{ option('xferlog_std_format', 'NO') }}
{{ option('nopriv_user', 'ftpsecure') }}
{{ option('ftpd_banner', '"Peerless Network Download Server"') }}
{{ option('chroot_list_enable', 'YES') }}
{{ option('chroot_list_file', '/etc/vsftpd/vsftpd.chroot_list') }}
{{ option('chroot_local_user', 'NO') }}
{{ option('hide_ids', 'YES') }}
{{ option('tcp_wrappers', 'NO') }}
{{ option('use_localtime', 'YES') }}
{{ option('userlist_deny', 'NO') }}
{{ option('userlist_enable', 'YES') }}
{{ option('userlist_file', '/etc/vsftpd/vsftpd.user_list') }}
{{ option('user_config_dir', '/etc/vsftpd/vsftpd_user_conf') }}